Method and device for manufacturing of saddle coils

ABSTRACT

The invention provides a method of manufacturing a saddle coil. The method comprises the step of winding a conductor around a winding core ( 12 ) which is at least partially inclined. During this step an intermediate coil is formed. The intermediate coil is bent to form the saddle coil.

FIELD OF THE INVENTION

[0001] The invention relates to saddle coils and to methods ofmanufacturing saddle coils. In particular, this invention relates tosaddle coils used in charged particle beam devices.

BACKGROUND OF THE INVENTION

[0002] Charged particles placed in an electrical or magnetic fieldexperience forces acting upon them. In an electrical field, the forcesare proportional to the field strength and are acting in the directionof the field vector. In a magnetic field, the forces on the chargedparticle moving through it are also proportional to the field strength,however, they are acting perpendicular to the field vector and to thevelocity vector of the particle.

[0003] These field properties are used in a variety of charged particlebeam devices to influence the path of the particles. Familiar examplesof such devices are oscilloscopes, computer monitors, television picturetubes, charged particle microscopes etc. In general, a charged particlebeam device comprises a particle source and one or more lenses whichusually operate in vacuum. Since the diameter of the beam coming fromthe particle source is in many applications too large, the lenses areused to reduce the diameter and to focus the beam. Further, in chargedparticle beam devices, deflection systems are often used to scan thebeam along a line and then displace the line position for the next scanso that a rectangular raster is generated on either a viewing screen ora specimen. A typical example of a deflection system is a scan coilwhich is positioned in close contact to the passing beam so that themagnetic field created by the scan coil influences the beam path.

[0004] In many applications the particle beam is guided through acylindrical tube e.g. a cathode ray tube (CRT) or a shielding tube ofcharged particle microscopes. In order to provide for a deflection fieldclose to the beam path, the coils are usually formed to adapt to theparticular radius and/or shape of the tube. Such coils are called saddlecoils. For charged particle devices, a saddle coil with an opening angleof about 120° is preferred. Saddle coils producing high accuracymagnetic deflection fields are also used in nuclear magnetic resonancedevices (NMR). In view of their more complex three dimensional shape,the production of saddle coils is more elaborate and costly than theproduction of flat coils (see also P. W. Hawkes and E. Kasper,“Principles of Electron Optics”, Vol. 2, pp. 836-839, Academic Press,1989).

[0005] In the state of the art, a variety of methods for producingsaddle coils are known. In U.S. Pat. No. 5,409,558 (Takahashi, Toshiba)a manufacturing method is disclosed according to which wires are placedin grooves formed in a first mold, so that the spatial arrangement ofthe saddle coils are determined by the positions of the grooves. This isdone to locate the wires in predetermined positions and to achieve aspecific spatial arrangement of the saddle coils.

[0006] In U.S. Pat. No. 5,773,724 (Unterseh, Endress+Hauser) anothermethod of manufacturing differently dimensioned saddle coils isdescribed. A prefabricated wire having a first insulating-varnishcoating directly thereon and a second insulating-varnish coating appliedto the first coating, the second coating having a baking temperaturelower than the softening point of the first coating. The coil is woundon a coil form to form a flat coil, the coil from being a prefabricatedpart of a flexible plastic which is dimensionally stable at the bakingtemperature. The flat coil is then fitted together with the coil form tothe curved surface of a corresponding dummy to form a stilldimensionally unstable saddle coil. Then a current whose strength is sochosen that the baking temperature is at least reached is sent throughthe saddle coil until the second insulating-varnish coatings are bonded,baked or fused to each other. After the current has been switched off,the second insulating-varnish coating solidifies to a dimensionallystable saddle coil.

[0007] U.S. Pat. No. 5,994,704 (Nakasuji, Nikon) discloses a method ofmanufacturing electromagnetic deflectors. A pair of looped shapedchannels are formed opposite each other in the sides of a cylindricalinsulating cylinder. An electrically conductive material is embedded inthe channels to form a set of opposing coils operable to deflect acharged particle beam passing through the cylinder. The cylinders areplaced concentrically inside a cylindrical outer casing made offerromagnetic material such as a ferrite to make an electromagneticdeflector.

[0008] The manufacturing methods known in the art still have thedisadvantage of requiring complicated process steps and/or various moldsfor the saddle coils.

SUMMARY OF THE INVENTION

[0009] The present invention intends to provide an improved saddle coiland a method for manufacturing a saddle coil to overcome at least someof the problems associated with saddle coils and manufacturing processesknown in the state of the art. According to one aspect of the presentinvention, there is provided a method for manufacturing saddle coils asspecified in independent claims 1 and 8.

[0010] According to a first aspect, the method comprises the step ofwinding a conductor around a winding core which is at least partiallyinclined. During this step an intermediate coil is formed. Thisintermediate coil is then bent to form the saddle coil. Thereby,conductor in the context of this invention comprises all continuouslength of conductive material with all kind of circumferences which canbe wound around a given shaped body. In particular, it includes wires,cables, filaments, etc.

[0011] The at least partially inclined section of the winding core willcause the intermediate coil, which is formed by winding a wire aroundthe core, to have a corresponding inclined section. Due to the inclinedsection, the windings will have an increasing wire length. If theintermediate coil is bent to form the saddle coil, the longer windingswill have sufficient wire length to allow for a plastic deformationduring the bending step.

[0012] According to a further aspect of the present invention there isprovided a saddle coil as specified in independent claim 9. Thereby, theinclined section of the intermediate coil acts as a wire lengthreservoir during the bending step. Windings of the intermediate corewith a bigger circumference can be bent further than those with asmaller one.

[0013] Further advantageous, features, aspects and details of theinvention are evident from the dependent claims, the description and theaccompanying drawings. The claims are intended to be understood as afirst non-limiting approach of defining the invention in general terms.

[0014] According to a preferred aspect of the present invention, thewinding core comprises at least two inclined sections. The correspondinginclined sections of the intermediate coil can cooperate to providesufficient flexibility of the coil during the bending step.Advantageously, the at least two inclined sections of the winding coreare located opposite to each other. If the bending is carried out insuch a way that both inclined sections are displaced, the two reservoirssupport each other in absorbing the stretching of the windings. It isparticularly preferred to provide for the same inclined slope at the atleast two inclined sections. Given a respective symmetry during thebending step, the saddle coil can be formed more evenly from theintermediate coil.

[0015] According to a further preferred aspect of the invention, theinclined sections of the winding core are straight. This allows to windthe conductor in such a way that a linear increase of wire length isachieved. A linear increase in wire length is advantageous during thebending step. It is further preferred to displace but not to bend theinclined side sections of the intermediate coil.

[0016] In another preferred method of manufacturing a saddle coil, thetwo core bow sections of the winding core are parallel to each other. Itis even more preferred that the two core side sections and the two corebow sections are perpendicular to each other. If the intermediate coilhas a higher symmetry it is easier to form a saddle coil which fits bestto conical or cylindrical shaped parts such as lenses and shieldingtubes placed around a charged particle beam. Thus, a highly accuratemagnetic field can be created.

[0017] It is further preferred to form a flat intermediate coil.Compared with other shapes, a flat coil is a lot easier to manufacture.

[0018] According to another advantageous object, those parts of theintermediate coil which are not inclined are bent. The bending ofcertain parts of the intermediate coil causes stress in other parts ofthe coil which are displaced but not bent. The other parts preferablyact as a wire length reservoir and thus have preferably a inclined crosssection.

[0019] It is of particular advantage to use the saddle coilsmanufactured in accordance with this invention in charged particle beamdevices. Primarily they are used for deflection systems where thedistance of the coils from the optical axis of the charged particledevice is limited either by the available space or where high deflectioncurrents and a corresponding heat load have to be avoided. In thesecases the homogeneity of the deflection field generated by planar coilsis not sufficiently accurate in the neighborhood of the optical axis.This is desired for magnetic deflection systems employed for beamalignment and beam scanning devices. A preferred application is amagnetostatic beam separator used for splitting the primary chargedparticle beam from the secondary and backscattered charged particle beam[described in EP 0 917 177 A1 Korpuskularstrahlgerät].

[0020] The invention is also directed to methods for manufacturing thedescribed saddle coil. It includes method steps for manufacturing everyfeature of the saddle coil. Furthermore, the invention is also directedto saddle coils manufactured according to the disclosed methods. Themethod steps may be performed by hand, by way of hardware components, acomputer programmed by appropriate software, by any combination of thethree or in any other manner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Some of the above indicated and other more detailed aspects ofthe invention will be described in the following description andpartially illustrated with reference to the figures. Therein:

[0022]FIG. 1a shows a winding tool with a partially inclined windingcore for forming an intermediate coil.

[0023]FIG. 1b shows the winding tool of FIG. 1a, the winding tool beingturned 90° ;

[0024]FIGS. 2a and 2 b show top views of winding cores;

[0025]FIGS. 2c, 2 d and 2 e show straight, concave and convex inclinedslopes of the winding core;

[0026]FIG. 3 shows a sectional view through an intermediate coil;

[0027]FIGS. 4a shows a front view of a bending tool with an intermediatecoil placed between mold and stamp;

[0028]FIG. 4b shows a side view of a bending tool with an intermediatecoil placed between mold and stamp;

[0029]FIGS. 5a to 5 d show top views of a variety of intermediate coil;

[0030]FIG. 6 shows a top view of a saddle coil according to theinvention;

[0031]FIG. 7 shows a side view of the saddle coil according to FIG. 6seen from the perspective of line A; and

[0032]FIG. 8 shows a side view of the saddle coil according to FIG. 6seen from the perspective of line B.

[0033] In the figures, like reference numbers refer to like elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034]FIG. 1a shows schematically an exemplary tool 10 used for windingan intermediate coil 3. Sandwiched between an upper holding plate 16 anda lower holding plate 17 is winding core 12. The lower holding plate 17is placed onto support shaft 18. The support shaft 18 can be providedwith a central rod extending from the top of the shaft. The rod isinserted into a corresponding opening in lower support plate 17. Then,winding core 12 with its fixation opening 22 is placed over the rod. Thelast part located on the rod is upper holding plate 16. A threading atthe top end of the rod interacts with nut 14 to fasten the winding core12 tightly between the upper and the lower holding plate. Preferably,lower support plate 17 and support shaft 18 are formed as a singlepiece.

[0035] Alternatively to a rod emerging from shaft 18, fastener 14 can bea screw which is screwed into a bore hole provided in shaft 18. In bothcases a tight fixation is preferred to prevent windings from glidinginto the interface between winding core 12 and one of upper and lowerholding plates 16,17. Advantageously, a washer 15 is placed betweenfastener 14 and upper holding plate 16.

[0036] The surface of the upper holding plate 16 facing the winding core12 is advantageously provided with a slit. It starts at the outer rimand ends at the center of the upper holding plate. The starting end ofthe wire for the winding is inserted into the slit so that it does notexceed above the surface of the upper holding plate. Even so it ispreferred to provide the upper holding plate 16 with the slit forinserting the wire, the slit can also be provided on lower support plate17. An intermediate coil is manufactured e.g. by inserting the startingend of a wire into the slit until it reaches the triangular comercreated by the upper holding plate 16 and the winding core 12. The wireis then wound around the winding core. After the first winding iscompleted, the second winding is started adjacent to the first one. Thefirst layer of windings is accomplished if present winding does not fitbetween the pre ultimate winding and the lower holding plate 17. Fromthat point on, the next layer is formed into the opposing direction i.e.starting from the lower holding plate 17 towards the upper holding plate16. The tension applied to the wire during the winding process, incombination with the inclined slope of the winding core, will cause aforce directed towards the upper winding plate 16. Nevertheless, arespective slip can easily prevented by carefully winding the wire inthe recess between two windings of the lower layer which will providefor sufficient friction. A fixing of several windings can also beachieved by using an insulating varnish around the wires. A heating stepcauses the varnish to melt and fixes the wires to each other.Alternatively, an appropriate solvent like alcohol can be providedbetween the wire layers.

[0037] The two holding plates 16, 17 act as upper and lower limitationof the intermediate coil which starts to build up with the completion ofeach consecutive winding layer. The last winding of each layer is firmlyheld in place by the preceding winding, the lower winding layer and oneof the two holding plates. If the desired number of winding layers hasbeen built up, the intermediate coil is completed. In some cases, thebent wires are sturdy enough to supply the resulting intermediate coilwith sufficient stability so that no further process steps are necessarybefore detaching the intermediate coil from the winding tool 10.However, it is preferred to use insulating varnish and a heating step oran appropriate solvent like alcohol for providing additional stabilityto the completed intermediate coil.

[0038] To detach the intermediate coil from the winding tool 10,fastener 14 is loosened and upper holding plate 16 removed. Then, theintermediate coil can be detached, either together with winding core 10or separately. For most applications, the detached intermediate coil isready for further processing.

[0039]FIG. 1b shows the winding tool 10 of FIG. 1a. The winding tool 10is turned 90° so that the inclined slopes of the winding core 12 aredirected parallel to the surface of the drawing sheet. The winding coreused in FIG. 1b is rectangular with two opposing inclined slopes and twoopposing straight sections. Both, the inclined slopes and the straightsections are parallel to each other. The resulting shape of the formedintermediate coil will be discussed with reference to FIG. 3.

[0040] The winding of the conductor onto the winding core 12 can becarried out manually or automatically. For the automatic winding a highsophisticated CNC machine is not required, in general, a simple windingmachine will do the job.

[0041] The winding tool for manufacturing the intermediate coilcomprises a winding core 12 with at least one inclined section, a firstholding plate for supporting the lower winding layers and a secondholding plate for supporting the uppermost winding layer.

[0042]FIGS. 2a and 2 b show a top view of two rectangular winding cores12. Both winding cores comprise two inclined slopes opposing each otherand parallel to each other. Together with two holding plates the windingcore 12 forms a mold for manufacturing the intermediate coil which ismade by winding a wire around it. In the embodiments shown, the inclinedslopes are arranged perpendicular to the remaining two sides of thewinding core 12. Depending on the material used for manufacturing thewinding core, the four corners created by at the intersection of theinclined slopes 20 with the remaining two sides have sharp edges whichcould cause rupture of the wire wrapped with tension around it.Preferably, these edges are rounded to reduce the danger of wire damage.

[0043] A fixation opening 22 located in the center of the winding servesto accommodate either a rod attached to shaft 18 of the winding tool ora bolt of fastener 14. To avoid rotation of the winding core during thewinding step, the fixation opening 22 is preferably non-circular. Asquare, a cross shaped or an elliptically shaped fixation opening forholding a guide member which fixes the winding core between two holdingplates has the advantage of preventing circular movement of the windingcore. However, the production of noncircular guide members engaging withcorresponding fixation openings are more costly to produce.

[0044] The winding cores shown in FIGS. 2a and 2 b have straightinclined sections and straight connecting sections. It is within thescope of this invention to also use curved sections which still allow atight winding of the wire onto the winding core 12. FIGS. 2c to 2 e showthree side views of various inclined slopes of winding cores. Thelinearly inclined slope of FIG. 2c has the advantage of providing alinear increase in wire length. Nevertheless, the concave and the convexinclined slopes shown in FIG. 2d are still capable of forming a inclinedsection in the intermediate coil which can then act as a wire lengthreservoir during the bending step.

[0045]FIG. 3 shows a cross sectional view of an intermediate coil. Theillustrated intermediate coil has been formed by winding a wire around awinding tool 12 which has two opposing inclined sections which runparallel to each other. The cross sectional view is taken along a lineperpendicular to the inclined slopes of the intermediate coil. Thedrawing shows two rhombus shaped wire bundles which represent the Nloops or windings 31 of a coil creating a specific magnetic field in theinterior of that coil 32 or in its vicinity. Winding 34 is part of awinding layer with smaller circumferences in comparison with the largercircumferences of the windings of the winding layer represented bywinding 33.

[0046] The intermediate coil 30 comprises a inclined slope 35 at itsinterior side. This slope was formed by winding the wires around theinclined part of winding core 12. A further inclined slope is located atthe exterior part 36 of intermediate coil 30. These slopes results froma transposition of the interior slope created by the steady build up ofintermediate coil 30. In practice, however, the transposition of theslope is not as perfect and clear as shown in FIG. 3. In most cases,small imperfections during the winding steps cause the diagonal line ofthe slopes to get reduced with the build up of each additional layer.From a certain number of layers on, the exterior side of theintermediate coil appears to be irregular.

[0047] The bending of intermediate coil 30 is achieved e.g. by applyinga force to the winding layer with the big circumference at the positionof the inclined sections. An opposing force is applied to the windinglayer with the small circumference at positions which are distinct fromthe inclined sections. This results in. This results in a bending of theintermediate coil into a saddle coil by causing a bigger deformation ofthose wire loops belonging to the larger circumference layer as comparedto the deformation of those wire loops which belong to the smallercircumference layer.

[0048] Preferably, one force is exclusively applied to the inclinedsections of the intermediate coil and another force is exclusivelyapplied to the non-inclined sections of the intermediate coil.

[0049]FIG. 4a shows a front view of a bending tool. The bending toolcomprises a forming mold 40 and a stamper 46. An intermediate coil 30 isplaced in between forming mold 40 and stamper 46 to better illustratethe bending step. The intermediate coil shown in FIG. 3 has beenmanufactured by winding a circular wire around a winding tool 12 similarto the one shown in FIG. 2a. Seen from above, the intermediate coil hasa rectangular shape comprising 4 straight sections (see also FIGS. 5a tod), in particular, two inclined slope sections being parallel to eachother and two bow sections which are also parallel to each other.

[0050] A side view of the two inclined slope sections of intermediatecoil 30 is shown in FIG. 4a and a side view of the two bow sections isshown if FIG. 4b. The number of windings in a wire bundle of each branchof the intermediate coil in FIG. 4a is different than the number ofwindings in a wire bundle of each branch of the intermediate coil inFIG. 4b. This was done to demonstrate that a huge variety of possiblesaddle coils can be formed with the disclosed invention. Both figuresshow a cross sectional view of the same bending tool whereby the viewingangle of the bending tool differs 90°.

[0051] The bending tool shown in FIG. 4a comprises a forming mold 40with a first slope 41 and a second slope 42. When the stamper pressesthe intermediate coil 30 into the forming mold 40, the interior inclinedslope 35 (FIG. 3) of the intermediate coil interacts with the firstslope of the forming mold. The downward movement of the stamper causesthe interior slope of the intermediate coil 30 to slide along the firstslope thereby creating a force directed away from the interior of thecoil. This results in a small clockwise rotation of left wire bundle anda small counter clockwise rotation of the right wire bundle. Thedownward movement of the coil is stopped by the first slope 41 ontowhich the lower side of the intermediate coil 30 gets to rest.Alternatively, it is also possible to use a bending tool with a firstand a second slope being arranged so that the intermediate coil duringthe bending step interacts with the second slope 42 first andsubsequently with the first slope 41. This can be achieved e.g. byextending second slope 42 in FIG. 4a.

[0052] The intermediate coil 30 experiences an upwardly directed forcecaused by the first and second slope 41, 42 which primarily acts onthose sections of the intermediate coil which comprise the inclinedslopes. At the same time, intermediate coil 30 experiences a downwardlydirected force caused by stamper 46 which primarily acts on the bowsections of intermediate coil 30. If a flat intermediate coil is used inthe bending step (which is the case in most applications), the bowsections are straight. They are called bow sections since the bow shapedextension 47 of stamper 46 will force these sections to adapt to the bowshape of extension 47.

[0053] In FIG. 4a, the forming mold comprises a guiding frame 43 forguiding stamper 40 during its downward moving into forming mold 40.Different to the figure, the guiding frame is preferably higher so thatstamper 46 can be inserted into the guiding frame 43 of forming mold 40before the stamper contacts intermediate coil 30.

[0054]FIG. 4b illustrates in particular the shaping action of the bowextensions onto those parts of the wire bundles which connect the twoparallel inclined slope sections. During the downward movement ofstamper 46, the lowest part of the bow extensions 47 of stamper 46contacts the wire bundle of intermediate coil 30 first. It contacts theintermediate coil approximately in the center of its bow sections. Then,the coil is forced downward until the inclined slopes of the coilcontact the first slope. At that moment, the inclined shaped wirebundles of intermediate coil 30 start to be rotated to the outside andthe bow sections of intermediate coil 30 start to be shaped under theinfluence of bow extension 47. At the end of the downward movement ofstamper 46, the lower part of the original intermediate coil rests onfirst slope 41 and the interior inclined slope of the originalintermediate coil rests on the second slope 42. At the same time, bowextensions 47 have formed the straight bow sections of the originalintermediate coil 30 into bent bow sections having a shape correspondingto the shape of bow extensions 47.

[0055] An exemplary stamper for carrying out the disclosed inventioncomprises a shaft part and bow shaped extensions. An exemplary formingmold for carrying out the disclosed invention comprises a slope whichinteracts with the interior slope section of the intermediate coil and,preferably, a further slope for interacting with the underside of theintermediate coil. Bow shaped in the context of this invention includesall shapes which are desirable for a saddle coil and which can beachieved by the interaction of a stamper and a forming mold. In case ofmore complex shapes of the final saddle coil, several bending steps canbe carried out consecutively. With each bending step, the (several)intermediate coils are brought in closer conformity with the desiredfinal shape of the saddle coil. Advantageously, between each bendingstep heat is provided to the intermediate coil.

[0056]FIGS. 5a to 5 d show a variety of top views of intermediate coils.All of them comprise four straight sections, two side sections 37 andtwo bow sections 38. The expression bow sections is derived from theirdestination of forming the later bowed sections of the saddle coils. Theside sections 37 connect the bow sections 38 and at least one of theside sections comprises a inclined slope part which acts as a wirelength reservoir during the bending step. In a bent wire bundle, thelength of each wire differs depending on its location in the wirebundle. If the bow of a saddle coil is shaped as section of a circle,wires having the same curvature but bigger radii have a bigger length.The inclined slopes in the side sections 37 of the intermediate coilstake account of this geometrical requirement of the bow sections 38 andallow the intermediate coils to be bent without risking damage or evenrupture of a winding. It should be noted that the bowed sections of asaddle coil do not necessarily have to be circular. Other bowed shapesare also included within the disclosure of this invention.

[0057] The side sections 37 in the square shaped and rectangular shapedintermediate coils of FIGS. 5a and 5 b are parallel to each other. Insuch an arrangement it is advantageous to provide both side sectionswith even slopes if a symmetrically shaped saddle coil shall bemanufactured. Nevertheless, it is possible that only one interior sideof the intermediate coil comprises a slope or that the slopes on bothinterior side differ from each other. Such an arrangement can beadvantageous if unsymmetrical saddle coils are formed.

[0058] The intermediate coils shown in FIGS. 5c and 5 d have sidesections 37 which are not parallel to each other. In particular theintermediate coil of FIG. 5c has a trapezoid shape. If the bow sections38 of this intermediate coil are formed in such a way that they have thesame curvature but different radii then the resulting saddle coil canclosely fit to a inclined shaped object such as an objective lens of acharged particle device. This also applies to the intermediate coilshown in FIG. 5d. The magnetic field of such a saddle coil will,however, not be symmetric to any plane perpendicular to the bow sections38. With respect to these intermediate coils, the winding tools and thebending tools need to be adapted accordingly.

[0059] In the context of this invention, it is not required that theside sections 37 and/or the bow sections of the intermediate coils arestraight. They can comprise curvatures or be composed of severalstraight sections with an angle in between each straight section.Naturally, the winding tools and the bending tools have to be adaptedaccordingly. Furthermore, it is not necessary that opposing sidesections 37 or bow sections 38 have the same shape. Geometricalvariations between opposing sections are possible. This gives themanufacturing method disclosed in this invention the flexibility to formalso more complex shaped saddle coils. Thereby, care has to be takenthat the intermediate coils are provided with inclined slope sections atappropriate positions to compensate for different wire length requiredby different layers of windings in bowed sections of the desired saddlecoil.

[0060] The angles at the intersections of side and bow sections in thefour intermediate coils shown in FIGS. 5a to 5 d are eitherperpendicular or deviate only a small angle from it. In general, biggerdeviations from 90° are not often required. However, in the windingprocess or for the creation of the magnetic field it can be preferred toround the edges where side and bow sections meet. This reduces the riskof damage of the wire which are wound with tension onto the edges (orcorners) of the winding core.

[0061] Intermediate coils in accordance with this invention comprise atleast one inclined slope section. This inclined slope section is capableof compensating for stress acting on different windings of theintermediate coil during a bending step. The saddle coils manufacturedin accordance with this invention are in particular used as miniaturizedsaddle coils.

[0062]FIG. 6 shows a top view of a saddle coil with bow section 38 beingbent into the plane of the drawing paper. FIG. 7 shows a side view ofthe saddle coil seen from the perspective of line A shown in FIG. 6,whereas FIG. 8 is a side view of the saddle coil seen from theperspective of line B shown in FIG. 6.

1. A method of manufacturing a saddle coil, the method comprising thefollowing steps: a) winding a conductor around a winding core which isat least partially inclined, thereby forming an intermediate coil; b)bending the intermediate coil to form the saddle coil.
 2. The method ofclaim 1, whereby the winding core comprises two core side sections, theside sections being inclined.
 3. The method of any of the precedingclaims, whereby the winding core further comprises two core bowsections, the core bow sections not being inclined.
 4. The method ofclaim 3, whereby the two core bow sections are parallel to each other.5. The method of any of claims 2 to 4, whereby the two core sidesections and the two core bow sections are perpendicular to each other.6. The method of any of the preceding claims, whereby the intermediatecoil is formed as a flat coil.
 7. The method of any of the precedingclaims, whereby the saddle coil is formed by bending those parts of theintermediate coil which were not formed adjacent the inclined sectionsof the winding core.
 8. A method of manufacturing a saddle coil, themethod comprising the following steps: a) winding a conductor to form anintermediate coil, the intermediate coil comprising is at least onesection which is inclined; and b) bending the intermediate coil to formthe saddle coil.
 9. A saddle coil, especially manufactured according toany of the preceding claims, obtainable by bending an intermediate coil,the intermediate coil comprising at least one inclined section.
 10. Thesaddle according to claim 9, whereby the intermediate coil comprises atleast one rhombic section.